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Expand off-grid capacity using grid tie microinverters

vallesj

vallesj

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If your system is at capacity, or getting too many shades, another option is to get panels with a micro grid tie inverter for each of them, that you could just connect to your off-grid AC circuity. That way shades on one panel does not reduce down your whole system production, you don't have to invest on thicker wire for panels. You just have to make sure to don't overload the circuit where you connect the panels.
I had 2 broken panels reducing my total production by 500 watts (confirmed after replaced them with new ones). I bought a micro for each of them and now one produces 50w and the other 40w (ideal capacity for each is 195W, or real numbers I am getting 150w). So with both individually only 210w are lost, because they are broken, but when on the system they were reducing 500W from them. So it is a good valid option.
 
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That only works if your off grid system is capable of AC coupling.
It must be able to control the grid-tied inverters.
 
vallesj said:
If your system is at capacity, or getting too many shades, another option is to get panels with a micro grid tie inverter for each of them, that you could just connect to your off-grid AC circuity. That way shades on one panel does not reduce down your whole system production, you don't have to invest on thicker wire for panels. You just have to make sure to don't overload the circuit where you connect the panels.
Click to expand...

You must use an off-grid inverter capable of AC coupling and controlling the microinverters. GT inverters don't regulate themselves. They assume an infinite grid in which to dump whatever they can deliver. The grid source inverter must be capable of "frequency shifting" to instruct the GT inverters to reduce/stop output.
 
Is the growatt 3000TL SPF-ES capable of AC coupling and controlling microinverters? I am not sure, and I don't think so...But I just added 2 GMI 180L (cheap chinese microinverters) and everything is working without an issue.
 
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Micro inverters expand your inverting capacity. If you have a constant load to dump/divert their production, that is fine. When load is removed, you should also disconnect the power supply from the micro inverters.
 
vallesj said:
Is the growatt 3000TL SPF-ES capable of AC coupling and controlling microinverters? I am not sure, and I don't think so...But I just added 2 GMI 180L (cheap chinese microinverters) and everything is working without an issue.
Click to expand...
No
And you have been lucky, so far.
 
sunshine_eggo said:
No.

As long as you ALWAYS have loads higher than those inverters produce, you'll be fine.
Click to expand...
My understanding is that inverters works similar to battery chargers, they don't force power into the battery, they just provide what the battery/load is requesting up to the capacity they have to produce. Or is there any problem/restriction that I am not aware off?
 
vallesj said:
My understanding is that inverters works similar to battery chargers, they don't force power into the battery, they just provide what the battery/load is requesting up to the capacity they have to produce. Or is there any problem/restriction that I am not aware off?
Click to expand...

You have GT inverters attached to an inverter not capable of AC coupling.

Your understanding is correct for INVERTERS... not GT inverters.
 
vallesj said:
My understanding is that inverters works similar to battery chargers, they don't force power into the battery, they just provide what the battery/load is requesting up to the capacity they have to produce. Or is there any problem/restriction that I am not aware off?
Click to expand...
Stand alone inverters only provide what is needed from them.
But grid-tied inverters produce everything that they can, and push it to the connected source. (Which isn't a problem for the massive grid)
 
Every day we learn something new... Thanks for the information! Yes I was lucky, but perhaps there is always a load higher than the 90w those GT inverters are pushing, but it is better to make sure that always be the case. Probably what I am going to do with these GT, so just feed connect them to the AC compressor, so they reduce consumption when turned on.
 
vallesj said:
Every day we learn something new... Thanks for the information! Yes I was lucky, but perhaps there is always a load higher than the 90w those GT inverters are pushing, but it is better to make sure that always be the case. Probably what I am going to do with these GT, so just feed connect them to the AC compressor, so they reduce consumption when turned on.
Click to expand...

That method works.
 
How long does it take to stop exporting when the contactor closes and how does the AC unit react to that?
 
Might take one to two seconds to stop producing power when contactor opens. The motor absorbs the little power. Likely not long enough to burn out the spinning motor.
 
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